Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/21/19

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
920 PM EST Fri Dec 20 2019 .SYNOPSIS... High pressure will remain over the East Coast through Saturday. A low pressure system will then develop over the Gulf of Mexico on Saturday and could bring precipitation to the forecast area on Sunday through Monday. Dry and warm high pressure builds in behind the departing low for the middle of next week. && .NEAR TERM /THROUGH SATURDAY/... As of 915 PM: Water vapor imagery and RAP 500 mb height fields show a closed upper-level low center moving east over the TX/OK border late this evening. Abundant mid and high-level moisture continues to spill east of this feature over the downstream ridge and across the southeastern U.S. High clouds will continue to thicken and lower across the region overnight, although the clouds may be briefly thin enough from time to time to permit temperatures to radiate down a bit cooler than previously forecast, and a modest downward adjustment has been made in a few locations. Otherwise, the combination of increasing higher clouds and moderating thicknesses will permit minimum temperatures to remain some two or more categories above Friday morning values. The ridge axis will move offshore tomorrow morning as the upstream H5 low gets cut off from the northern stream. By the end of the period late Saturday, the upper low is expected to be centered over the ArkLaTex area as upper-lvl divergence increases over our fcst area. At the sfc, the center of broad high pressure will continue to shift to the NE but remain in a proximity to support an incipient weak wedge by Saturday evening. By this time, a low will develop over the Northern Gulf of Mexico and begin to move towards our area. The models have been slowing the development of this system over the past few runs, and currently they suggest that the deeper moisture associated with the low won`t begin moving into our southern zones until Sat. night. As such, PoPs were limited to only slight chance over our southernmost zones towards the end of the period. For Saturday, high temps are expected to remain slightly below climatology as more cloud cover and weak wedging remain in place. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... As of 111 PM EST Friday: The models remain in relatively good agreement with the track and evolution of a closed upper low, expected to track over the ArkLaTex region Saturday night and then along the nrn Gulf Coast region Sunday through Monday. Fortunately, there is no phasing with the nrn stream, which keeps a broad upper ridge in place over the Great Lakes and Midwest, thus we are cut off from any cold air source. So, apart from a very minor concern over the nrn mountains at onset Saturday night, the passage of this low should be all rain. How much is the main fcst problem, but first a brief note about the onset. The model guidance continues to delay the nwd movement/spread of the light precip well ahead of the low on Saturday night, to the point where the guidance now suggests nearly the entire region with perhaps the exception of northeast GA would remain dry through daybreak Sunday. The new fcst package will blend in the slower guidance, such that our p-type trouble zone would only have a slight chance of precip before temps warm enough above freezing to no longer worry. If anything, the trend suggests we can sidestep the whole issue. Precip chances should gradually increase from the south on Sunday as the low reaches the Gulf Coast, but the northward push will be fighting the dry air in high pressure over the central Appalachians and Mid-Atlantic region. Again, precip prob was trimmed back based on the new guidance. Eventually, however, this should all be overcome late Sunday and Sunday night as the best mid/upper forcing comes into play. For now, though, we keep the wrn Carolinas in a precip prob gradient, with the categorical across the south, likely in the middle, and still only a chance n of I-40. The low should pass by to our south on Monday, and so precip prob starts to tail off, still favoring the srn/ern zones. The best potential for heavy rain should be across the srn-most part of the fcst area, especially the Lakelands, but I am wary of the QPF. This looks something like a situation where we end up with less rainfall than expected. The passage of the upper system to our south will result in a stronger-than-normal easterly flow off the Atlantic, but much of that moisture might be intercepted by convective elements that form in the stronger isentropic upglide over the coastal plain and coastal front. The upshot is that by my estimation, if anything our QPF is more likely to be overdone than underdone. It would be too early to contemplate any Watches at any rate. Temps will be slightly below normal Saturday as precip develops, but above normal on Monday. The upper system moves away Monday night and the precip should end from southwest to northeast by daybreak Tuesday. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 205 PM EST Friday: The medium range forecast looks exceedingly quiet for late December. In the wake of our upper low, an upper ridge will build in from the west for Tuesday and will flatten for the middle part of the week. Dry high pressure will be the rule for the Christmas holiday and again on Thursday, with temps running well above normal. By Friday, the pattern may begin to amplify as another upper trof comes eastward out over the Plains. The only issue will be if moisture can return fast enough to result in the development of some upslope showers by the end of the day. The ECMWF is slower than the GFS, and dry, so for now we keep the precip chances below 10 pct. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... At KCLT and elsewhere: High clouds will continue to thicken and lower through the terminal forecast period. Anticipate cigs AOA 20 kft early, dropping closer to 10-12 kft by tomorrow night. Winds will remain very light, but gradually acquire more of an ENE to NE flow component through the period. The main exception will be more SE to S flow at KAVL through Saturday. All terminal locations should remain dry through the period, with perhaps just spotty light rain or showers beginning to encroach from the south on the Savannah River Valley areas by 00Z Sunday. Outlook: a Gulf storm system is expected to bring widespread rain to the region perhaps as early as Saturday night, but more likely Sunday into Monday, with associated restrictions possible. Dry conditions should return by Tuesday and persist through the middle of next week. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 100% High 100% High 100% High 100% KGSP High 100% High 100% High 100% High 100% KAVL High 100% High 100% High 100% High 100% KHKY High 100% High 100% High 100% High 100% KGMU High 100% High 100% High 100% High 100% KAND High 100% High 100% High 100% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...HG/JPT SHORT TERM...PM LONG TERM...PM AVIATION...HG/JPT
Area Forecast Discussion...UPDATED
National Weather Service Hanford CA
354 PM PST Fri Dec 20 2019 Updated Air Quality Issues section .SYNOPSIS...Dry weather and mild afternoon temperatures can be expected over the district into Saturday. A storm system will bring rain and high elevation snow to the region from Sunday morning into Monday afternoon along with cooler temperatures. A weak, but colder system will impact the region toward Christmas eve. An active pattern remains into next week. && .DISCUSSION... Ridge remains in place across the desert southwest which has given us another nice, dry day across the Central California interior. High temperatures will end up in the low to mid 60s in the valley, which is 4 to 8 degrees above average. The ridge will continue to shift toward the east on Saturday and another warm day is expected across the area ahead of approaching system. Very strong southeasterly winds will begin to develop on Saturday morning in the Fort Tejon and Tehachapi area and continue into Sunday afternoon. Latest high-resolution HRRR and NAMNEST are producing very strong winds, with localized gusts up to 65 mph, especially in the Grapevine area. For this reason, a High Wind Watch has been issued for the Fort Tejon and Tehachapi zones beginning Saturday morning through Sunday morning. Gusty winds are also possible in the West Side Hills on Saturday and Sunday, and a wind advisory might be needed for this area. Temperatures on Saturday will be a few degrees warmer than today, with afternoon highs getting into the mid to upper 60s in the valley. The upper level trough and associated front moves into the region on Sunday. Model guidance has been in better agreement on the timing of the start and end of the heaviest precipitation. Of note, RFC precipitation guidance has slightly increased precipitation amounts, and subsequent snowfall totals in the Sierra have also increased. A Winter Weather Advisory has been issued for elevations above 4500 feet in the Central Sierra, including Yosemite, Sequoia, and Kings Canyon National Parks from 7 AM PST Sunday until 10 AM PST Monday. General snowfall amounts will range between 5 to 10 inches, with locally heavier amounts. Precipitation within the valley will begin in the early Sunday morning in Merced and Mariposa counties before spreading southward toward Kern County by the afternoon. For precipitation totals from Sunday into Monday morning, between 1/4 and 1/2 of an inch is possible in eastern Merced, Madera, and Fresno Counties while up to 2/3 of an inch is possible in the Madera and Mariposa foothills. Due to our rain shadow, all other areas in the valley will generally be 1/4 of an inch or less, especially into Kings and Kern Counties. With a more favored orographics in the Fort Tejon area, up to 1/2 of an inch of precipitation is possible, and snow levels will remain generally above 5500 feet. Finally, desert locations can expect between 1/10 of an inch in the Indian Wells valley to 1/4 of an inch elsewhere. On Monday into Tuesday, near-term models continue to dig a deep upper level trough into the Southern California/Baja area, with the corresponding surface low forming off the Southern California coast by Monday morning. Precipitation is expected to move inland late Monday into early Tuesday, but the overall confidence in precipitation amounts is low at this time. What has more confidence is that as the cold core low moves over the region, snow levels are expected fall as low as 4000 feet by Tuesday morning. So, given the busy holiday travel time, possible impact-based warnings may need to be considered for this Christmas week system. Going forward from Wednesday onward to the end of the forecast period next Friday, the pattern remains active with models showing another system starting to impact the area by late Wednesday. However past this point, longer-term models are in very little agreement as the ECWMF digs a deep cutoff low off the CA coast while the GFS has a more transient upper level pattern. && .AVIATION... Strong southeasterly sustained winds of 20 to 30 kts, with local gusts up to 55 kt are likely in the Tehachapi mountains and valley- facing side of the Coastal Range starting 12Z Saturday into 18Z Sunday. Otherwise, VFR conditions will prevail over the central California interior during the next 24 hours. && .AIR QUALITY ISSUES... On Saturday, December 21st, 2019, fireplace/wood stove burning status is: no burning unless registered in Fresno, Kern, Kings, and Madera Counties. Further information is available at && .CERTAINTY... The level of certainty for days 1 and 2 is medium. The level of certainty for days 3 through 7 is medium. Certainty levels include low, medium, and high. Please visit for additional information and/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 7 AM Sunday to 10 AM PST Monday for CAZ192>194. High Wind Watch from late tonight through Sunday afternoon for CAZ196-197. && $$ public...CMC aviation....Andersen
Area Forecast Discussion
National Weather Service Jacksonville FL
815 PM EST Fri Dec 20 2019 .UPDATE... No major updates made to the forecast this evening. A coastal trough was lifting northward over the coastal waters, and this has shifted the bulk of the scattered light showers northward into southeast Georgia. Isolated showers are possible elsewhere along the coast overnight. Overnight lows will be in the low to mid 40s across interior southeast Georgia, the upper 40s to low 50s across coastal southeast Georgia and interior northeast Florida, and the mid 50s to around 60 degrees for the northeast Florida beaches. && .PREV DISCUSSION [619 PM EST]... .Near Term.../through Tonight/... A trough will be located along the Atlantic coast through Tonight. This feature will provide for gusty winds, especially at the beach communities. Lift and convergence associated with the trough will also provide for a chance for showers, mainly at the coast. Temperatures will trend above normal. .Short Term.../Saturday through Tuesday/... ...Potential for heavy rain this weekend... The region will be between a trough of low pressure along the Atlantic coast, and an area of low pressure gathering over the central gulf. Much of Saturday will be dry, with the best chances for showers near the coast. The warm front associated with the low is expected to move through late Saturday night through Sunday. While the models differ in track and timing, the best potential for heavy rain will be in the overnight Saturday night through Sunday timeframe. The location of the heaviest rain is still in question, but a wet period is forecast for the entire forecast area. Gusty winds will also be expected, especially along the coast. The low itself is expected to track east across the forecast area Sunday night through Monday night. A few periods of heavier rain will be possible with the low passage as well, but there will likely also be periods of dry weather. Rain chances will decrease from west to east on Tuesday, as the low pulls further to the east. Temperatures will trend above normal through Sunday, near normal Monday, then above normal Tuesday. .Long Term.../Tuesday night through Friday/... High pressure will build to the north Tuesday night into Wednesday, then to the northeast Thursday into Friday. While the chance for rain will not be zero this period, the chance is too low for mention at this time. Temperatures will trend above normal this period. .AVIATION... [Through 00Z Sunday] MSAS analysis shows decent surface moisture flux convergence along mainly the Florida coast. Inverted low pressure trough located about 50-60 miles offshore. KJAX radar depicts bands of shallow low topped showers moving inland at 25 knots across NE FL. Latest HRRR indicates these showers will focus on the JAX METRO area and eventually KSSI by 05Z as the rainbands translate slowly northward tonight. VFR/MVFR with northeast winds 5-10 knots inland, and 10-15 knots with gusts to 20 knots at KSSI and KSGJ. On Saturday, MVFR at KSSI and KSGJ with northeast winds 15 to 20 knots and occasional showers moving inland from Atlantic waters, mainly after 18Z. Inland TAF sites VFR with northeast winds 10-15 knots and a few showers for JAX METRO. Just beyond the TAF period, IFR conditions develop Saturday Night as rain associated with a strong low pressure system moves into the forecast area from the west. .Marine... A coastal trough will provide enhanced flow through Saturday. An area of low pressure will gather over the central gulf during the weekend. The associated warm front will cross the region Saturday night through Sunday. The low itself will cross the area Sunday night through Monday night. Winds and seas will remain elevated through the weekend into early next week. As the low moves east Tuesday, high pressure will build to the northwest then north toward mid week. Rip Currents: SE GA moderate risk through Saturday NE FL high risk through Sunday && .PRELIMINARY POINT TEMPS/POPS... AMG 43 57 49 62 50 / 20 20 80 80 80 SSI 51 60 56 64 53 / 40 30 70 90 90 JAX 53 64 57 68 52 / 50 30 70 80 80 SGJ 57 70 60 70 52 / 20 60 60 80 70 GNV 53 69 59 69 51 / 20 20 60 80 60 OCF 54 73 59 72 52 / 10 20 60 80 60 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Saturday evening for Coastal Duval- Coastal Flagler-Coastal Nassau-Coastal St. Johns. GA...None. AM...Small Craft Advisory until 3 AM EST Tuesday for Coastal waters from Altamaha Sound to Fernandina Beach FL out 20 NM- Coastal waters from Fernandina Beach to St. Augustine FL out 20 NM-Coastal waters from St. Augustine to Flagler Beach FL out 20 NM-Waters from Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-Waters from Fernandina Beach to St. Augustine FL from 20 to 60 NM-Waters from St. Augustine to Flagler Beach FL from 20 to 60 NM. &&
Area Forecast Discussion
National Weather Service Key West FL
1054 PM EST Fri Dec 20 2019 .DISCUSSION... Our winds have backed away from occasional gale-force gusts over the waters late this evening, but strong east-northeast breezes continue thanks to the tight pressure gradient between a stalled front over the southern Straits and a strong high pressure center over the U.S. Mid-Atlantic region. Radar shows a few weak showers or areas of light rain over the oceanside waters of the Keys this evening. Mesoscale models such as the HRRR show light rain expanding across the island chain overnight before retreating and withering away around mid-day Saturday. In fact, some weak subsidence on Saturday afternoon will lead to more cloud breaks and temporarily beat back our rain chances. Beyond Saturday afternoon, we will be watching with interest the development of a low center over the Central Gulf. It will deepen and expand as it moves across the northeast Gulf on Saturday night and Sunday morning. At first, it will bring the stalled boundary over the southern Straits back north across the Keys as a warm front around Sunday morning. As warmer and moister low-level air spreads back north, weak to moderate instability will develop. Warm fronts commonly come with a strongly veered wind profile and that will be the case here. Such a wind profile is favorable for organizing and sustaining convective updrafts, but the lack of strong instability will be the main limiting factor. The most likely place to get strong or possibly severe storms on Sat night/Sunday morning would be our far western Gulf waters near the Dry Tortugas. On Sunday evening, a cold front trailing from the low center will enter our western waters, eventually exiting our eastern waters on Monday morning. This front is likely to be accompanied by a broken squall line of thunderstorms. Any discrete cells that develop in advance of the main squall line will find a more favorable environment of both stronger instability and wind shear for sustaining updrafts and organizing convection. Convective wind gusts of 40-45 knots appear to be the main threat at this time. Will be watching this setup. The SPC Day 3 outlook currently has the Keys in a marginal risk of severe weather on Sunday and Sunday night. && .MARINE... Have removed the Gale Watch from the remaining waters, since it no longer looks like there is much possibility to hit a gale-force wind. Recent wind obs shows the start of a slow decreasing trend in speeds that should continue through sunrise. Nonetheless, strong to near-gale NE-E breezes will continue under a tight pressure gradient between a stalled front over the southern Straits and strong high pressure centered over the U.S. Mid- Atlantic region. Things will start to change more noticeably on Saturday. Low pressure will develop over the central Gulf, deepening as it moves through the northeast Gulf on Saturday night and Sunday morning. A trailing cold front will cross the Keys waters late Sunday into early Monday. The cold front will be followed by a shift to strong west-northwest breezes. Low pressure will then exit further and further east into the Atlantic on Tuesday and Wednesday, and high pressure will settle southward into the Southeast U.S.. && .AVIATION... Radar shows a few areas of sprinkles or light rain over the Straits adjacent to the Keys this evening. Several pieces of model guidance suggest a temporary expansion of the light rain across the island terminals late tonight and Saturday morning, or from about 10z-16z. On Saturday afternoon, model time-height sections show a modest increase in subsidence, which should help to scatter and thin out some of the lower cloud layers. Have therefore shown some improvement in sky cover on Saturday afternoon. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...Small Craft Advisory for GMZ031>035-042>044-052>055-072>075. && $$ Public/Marine/Fire...Haner Aviation/Nowcasts....Haner Data Collection......KBL Visit us on the web at Follow us on Facebook and Twitter at:
Area Forecast Discussion
National Weather Service Norman OK
541 PM CST Fri Dec 20 2019 .DISCUSSION... 00Z TAF discussion. && .AVIATION... MVFR ceilings will overspread most sites quickly over the first couple of hours of the forecast. The exceptions will be CSM/WWR which should remain VFR. Could see some IFR conditions develop late tonight in central Oklahoma along with some potential for drizzle. MVFR ceilings may linger through much of the day Saturday as well. Winds will remain light. && .PREV DISCUSSION... /issued 403 PM CST Fri Dec 20 2019/ DISCUSSION... There is a chance for drizzle/light rain over southern/eastern OK this afternoon into tomorrow morning as the closing low pressure trough tracks across southern OK overnight. Patchy fog is also possible early tomorrow morning across western OK and western north TX, and there is the possibility of more widespread fog Sunday morning. Latest water vapor loop (21Z) places the center of the upper low near Childress, TX with the midlevel dry slot covering the western two thirds of Oklahoma. Low-level clouds developed over southern/central portions of the state this morning and are still present. Forecast soundings from both the RAP and NAM suggest that light rain might be possible farther north into southern portions of the OKC metro overnight as well, and have thus bumped up the POPs slightly for this area. Added drizzle to north OK tonight, where low level saturation is suggested to be more shallow. In addition, parts of western north TX and western OK may see patchy fog early tomorrow morning. More widespread fog appears possible Sunday morning as multiple sounding sites indicate light winds and saturation beneath a sharp surface inversion. Sunday into Tuesday, daytime highs will trend upwards into the 60s. Winds are forecast to increase Sunday into Monday and RH values will drop to 15-20 percent across western Oklahoma - an enhanced fire weather risk appears possible. The next cold front is expected on Wednesday and high temperatures will return to the 50s by Thursday. Models have not been very consistent with precipitation for middle of next week. However, precipitation appears more likely toward the end of next week and into next weekend. For now, not enough evidence to introduce wintry precip, but will need to watch for changes in thermal profiles as the event draws closer. Thompson && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 36 50 33 57 / 10 10 0 0 Hobart OK 30 53 29 59 / 0 10 0 0 Wichita Falls TX 39 50 32 62 / 10 10 0 0 Gage OK 24 54 28 65 / 0 10 0 0 Ponca City OK 32 50 30 57 / 0 0 0 0 Durant OK 39 48 34 57 / 40 30 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ 14/30/30